System for the transmission and reception of radiant energy



SYSTEM FOR THE TRANSMISSION AND RECEPTION OF RADIANT ENERGY Filed NOV. 12 1929 @11 VEN J HHS l-l MOND JR.

WW ATTORNEY Patented Oct. 10, 1 933 SYSTEM FOR THE TRANSMISSION AND RECEPTION F RADIANT ENERGY John Hays Hammond, Jr., Gloucester, Mass.

Application November 12, 1929 Serial No. 406,566

Claims.

An object of this invention is to provide an improved system for the transmission and reception of radiant energy.

A further object of this invention is to provide a 5 an improved method for the transmission and reception of radiant energy.

A still further object of this system is to provide an improved system and method for the transmission and reception of radiant energy 1) whereby a high degree of secrecy may be obtained.

Further objects of this invention will become apparent from the following specification taken in connection with the appended claims.

In carrying out the object of this invention, a high frequency carrier wave is modulated by a low supersonic secondary frequency, the frequency of which is altered totransmit the dots composing the elements of a message, and differently altered to transmit the dashes composing the elements of a message.

At the receiver, means are provided for heterodyning the incoming frequency and producing the same audio frequency regardless of whether the secondary frequency received is that representative of the dot or dash. The. means for doing this comprise a heterodyne for cooperation with each of the two secondary frequencies present, which heterodynes will differ from each of 30 the secondary frequencies by the same given audio frequency. It is obvious that a single heterodyne may be so chosen that it will differ from each of the secondary frequencies by the same amount and thereby produce the same audio frequency regardless of which secondary frequency is being received.

Having thus briefly described my invention, attention is invited to the accompanying figures wherein Fig. '1 represents the transmitter adapted to transmit high frequency energy modulated in accordance with my invention.

Fig. 2 represents a receiver .for cooperation with the transmitter of Fig. 1 which receiver utilizes two heterodynefrequencies.

Fig. 3 represents an alternative receiver for cooperation with the transmitter of Fig. 1 which receiver utilizes a single heterodyne source. Having thus briefly described the figures embodying my invention, particular attention is in- 50 vited to Fig. 1, in which, represents an intermediate frequency oscillator with its associated circuits, and 11 represents the high frequency oscillator and its associated circuits. The frequency of oscillator 11 is adapted to be modulated by the intermediate frequency produced by the oscillator 10.

The frequency determining circuit of the intermediate frequency oscillator 10 is represented generally by 12 and comprises a plate inductance 13 and the condensers 14, 15 and 16 connected in series. The double action key or bugf; 17 having contacts 18 and 19, is so connected that when in the left-hand position, such as for the transmission of dots, condenser 16 is short circuited While in the right-hand position, such as, for in--' stance, for the transmission of dashes, both of' the condensers 15 and 16 may be short circuited. It is obvious that various arrangements maybe made for altering the-secondary frequency variqously for the transmission of dots and dashes, but each of these systems has the common feature that the secondary frequency is differently altered for the transmission of dots than for the transmission of dashes.

The high frequency energy produced by the oscillator 11 is thus modulated by the intermediate frequency and is transmitted in the usual manner through the antenna circuit generally indicated at 20. j

Referring now more particularly to Fig.2, 21 indicates generally the antenna system of the receiver, which is inductively coupled as shown in the input of the first detector 22. The output of the detector 22 is fed to the input of the two amplification circuits and 26 which are tuned to the intermediate frequencies resulting from the transmission of the dots and dashes, respectively, transmitted by the transmitter of Fig. 1. The oscillators 23 and 24 are also fed in the input of the amplifier tubes 25 and 26, and the frequency produced by these oscillators is adapted to combine with the secondary frequency present in the inputof the respective amplifiers. y

For detecting the audio beats produced by said combining there are provided the second detectors 27 and 28 respectively, whichare each adapted to produce the same audio frequency. The audio frequency thus produced is combined in the input of the amplifier 29. For'utilizing the amplified audio frequency, there is provided the work circuit represented in this instance by the telephone receivers 30.

Referring now more particularly to Fig. 3,.there is indicated generally at 31 the antenna circuit which is adapted to supply the first detector 32 in a similar manner to that previously described I in connection with Fig. 2. The amplifiers 35 and 36 are supplied bythe output of thefirst detector 32, and also by the local heterodyne 33, the frequency of which is so chosen as to differ from each of the frequencies used by the same amount. The outputs of the amplifiers 35 and 36 are fed tothe second detectors. 37 and 38 respectively, and upon the'production of the audio frequency, it is fed into the amplifier'39 and utilized by the receivers 40 in the same man ner as described in connection withFig. 2.

I will now briefly describe the operation of my system. Suppose, for instance, that the. os-

ice

its

cillator 10 produces a frequency of kilocycles with the key open, then it can be arranged to produce 22 kilocycles with the key to the left and the condenser 16 short-circuited for the transmission of a dot and to produce 20 kilocycles with the key to the right, and the con densers 15 and 16 short-circuited. Then at the receiver, the oscillators 23 and. 24 could be set at 23 and 19 kilocycles respectively, which would give an audio beat of 1,000xcycles'in the output of the second detectors 2'7 and 28 respectively, or as shown in Fig. 3, the oscillator 33 could be set at 21 kilocycles which would similarly give a beat frequency of 1,000 cycles in the output of the second detectors 3'] and 38 respectively. *Thus, it can be seen, that, with respect to the listeners on the receiver or 40 the same audio frequencyis present, representative of a dot or a dash regardless of the fact that a. different secondary frequency is being utilized for the transmission of said dot and'said dash. This itean readily be seen is different from the operation of a receiver 'of the ordinary type in which but a single secondary frequency could be obtained and either the dots or the dashes would be entirely missing in the final output, thusproducing secrecy of transmission which is one of the objects of the present invention.

Having thus described-my invention, it is to be understood that the system shown and described is'subject to numerous modifications all of which would have the common feature which I claim, and that I am therefore not to be limited by the specific form shown and described for the purpose of illustration only butby the actual scope of my invention as set forth in the appended claims. a

' WhatIclaim is: i 1. The method for the transmission and reception of radiant energy which comprises generating a current of highfrequency, generating a current of intermediate frequency, altering said intermediate frequency to send a dot, differently altering said intermediate frequency to send a dash, modulating said'high frequency current by said intermediate frequency current, transmitting the high frequency current thus modulated, receiving the modulated high frequency current, detecting said current to produce current of the intermediate modulation frequencies, locally producing a current of secondary fre quency, selectively modulating the secondary modulation frequencies received with said locally produced current of secondary frequency to produce a constant audio frequency current regardless of the transmitted modulation frequency, detecting said audio frequency resulting from each of the intermediate frequencies and combining said audio frequencies to produce a signal.

2. Apparatus for the transmission and reception of radiant energy which comprises a source of high frequency energy, a source of intermediate frequencyienergy comprising means for altering thefrequency of said energy including a double action key, a condenser" adapted to be short circuited when the key is closed in one direction, a second condenser adapted to be short circuited when the key is closed in the opposite direction whereby the frequency of said intermediate frequency isvaried in accordance with the position of said key, means for modulating said high frequency energy by said'intermediate frequency energy as thus varied, means for transmitting the high frequency energy thus modulated, means for receiving the energy thus transmitted, means for detecting the secondary frequency components of said received energy, heterodyning means for producing a heterodyne frequency which when ,said supersonic frequency components with said heterodyning frequencies, independent means for detecting each of the audio frequencies produced by said combining, means for combining and amplifying the audio frequency thus produced, and means for utilizing the audio frequencies thus combined and amplified.

3. Apparatus for the transmission of radiant energy which comprises a source of high frequency energy, a source of low'supersonic frequency energy comprising means for altering frequency ofsaid energy including a double action key, a condenser adapted to be short circuited when the key is closed in one direction, a second condenser adapted to be'short circuited whenthe key is closed in the: opposite direction whereby the frequency of said low supersonic frequency is varied in accordance with the position of said key, means for modulating said high frequency energy by said low supersonic frequency energy as thus varied, and means for transmitting th high frequency energythus modulated.

4. Apparatus for transmitting and receiving radiant energy which comprises, a source of high frequency energy, means for generating intermediate frequency energy, means for. altering the frequency of said last-named energy from one value to another value for sending different portions of a message, means for modulating said high frequency energy by said varied intermediate frequency energy, means for transmitting the high frequency energy thus modulated, means for receiving. the energy thus transmitted, comprising a detecting system for. detecting the. intermediate frequency components of said received energy, heterodyning, means for. producing heterodyne frequencies of such values that when combined with each of the said detected intermediate frequency components there, willresult the same audio frequency,.means for combining said intermediate. frequency components with said heterodyning frequencies, means for detecting the resultantenergy produced by said combining, and means for utilizing the resultant audio free quency. 1

5. Apparatus for transmitting and. receiving radiant energy which comprises, a source of high frequency energy, means for generating inter.- mediate frequency, energy, means foraltering the frequency .of said last-named energy from one predetermined value to another for sending different portions of a message, means for modulating said high frequencyenergy by said varied intermediate frequency energy, means for transmitting the high frequency energythus modur lated, means for receiving the energy thus transmitted comprising a detecting system for detecting the intermediate frequency components of said received energy, a generator adapted to generate energy of a frequency intermediate the frequencies of the two values of saidintermediate frequency energy, means for combining said intermediate frequency components with said heterodyning frequency, means for detecting the resultant energy produced thereby and means for utilizing the resultant detected energy.

JOHN HAYS HAMMOND, in. 

